A wind turbine transforms the energy of the wind into electrical energy. Therefore the wind turbine comprises a rotor, comprising a hub and rotor blades. The rotor blades interact with the wind.
The wind rotates the rotor of the wind turbine. The rotation is transferred to an electrical generator and is transformed into electrical energy.
The rotor blades are rotatable around their longitudinal axis to regulate the influence of the wind on the rotor of the wind turbine. The rotor blades are connected to the hub via a bearing to allow this rotation. The rotor blade is connected to the bearing by bolts and the bearing is connected to the hub by bolts.
A wind turbine is planned to have a lifetime of around 20 years or more. Service and maintenance is necessary during the lifetime of the wind turbine. Also the blade bearing is subject to maintenance and service. This may include inspection of the bearing, retightening the bolts, or exchanging the sealing of the bearing.
To perform the maintenance, access needs to be provided to the bearing, so that workers can reach the respective parts of the bearing. The maintenance and service work at the hub is performed at the wind turbine at hub height. The hub height of a wind turbine often is 80 meters and more, nowadays the hub height can also exceed 100 meters.
Service and maintenance work needs to be performed at both sides of the bearing. Thus the bearing needs to be accessed from the inside and from the outside. Thus workers need to access the rotor blade bearing from outside of the hub, too. The hub of the wind turbine is a casted piece of metal. Often the hub is covered by a spinner housing. The worker can access the bearing from the space between the hub and the spinner housing.
In the last few years the wind turbines get more powerful and thus the wind turbine itself gets bigger.
With the increasing size of the wind turbine, the hub is no longer covered by a spinner housing. Thus the maintenance work needs to be performed from outside the hub. Thus the worker needs to leave the hub at a hub height of for example 100 meters, and needs to perform the work as an outside work. The worker is thus exposed to wind and weather. The maintenance work in addition bears a safety risk for the worker. Some countries already prohibit the work to be performed outside of the wind turbine housing.
The aim of the invention is therefore to provide an improved access to the rotor blade bearing to perform maintenance and service work at the bearing.